a. and sb. Comp. Anat. [f. URO-2: see HY-OID a. and -AL 1.] a. adj. Forming or relating to a median posterior process or part of the hyoid arch in fishes or birds. b. sb. The bone forming this.
1835–6. Owen, in Todd’s Cycl. Anat., I. 345/1. The superior larynx [in birds] … rests upon the uro-hyal element of the os hyoides. Ibid. (1848), Archetype & Homol. Vertebr. Skel., 69. In most others [sc. fishes] there is … another … bone, which expands vertically as it extends backwards, in the middle line, from the basihyals; this is the ‘urohyal.’
1888. Rolleston & Jackson, Anim. Life, 93. A thin median bone, the basi-branchiostegal (= urohyal of Huxley).
